not by weather, but technology. the third largest airline still is not back on schedule this morning after a massive computer crash left thousands of passengers stranded. >> systems are down. i tried to check in online. the app isn't working. >> very frustrating. upsetting. not happy at all. >> reporter: the crash in computer system meant every ticket agent and gate agent saw their screens go dark. the same at the airline's operations center. no way to track bags, update schedules or flight plans. american had no choice. it stopped everything, grounding every plane. they were parked in chicago, miami and dallas. >> there's nothing you can do. you just have to stand in line and hope you can get on your flight. >> reporter: the cancellations started cascading before the day was over. nearly 800 flights never happened. embarrassed the ceo took to youtube to explain. >> unfortunately, in this case we had a software issue that impacted both our primary and backup systems. >> reporter: so all the airline could do was apol